Posted on by Matt Williams

Who Are The Most Famous Astronauts?

Apollo 11 Crew Photo. Credit: NASA

There have been many astronauts who have made tremendous contributions to our knowledge of space. But asking “who is the most famous?” is somewhat tricky. For one, its a bit subjective. And second, it can be hard to objectively measure just how important and individuals contributions really are. Surely, all astronauts are deserving of recognition and respect for their bravery and contributions to the pursuit of knowledge.

Nevertheless, in the course of human space exploration, some names do stand out more than others. And some have made such immense contributions that their names will live on long after we too have passed away. So without further ado, here are just a few of the most famous astronauts, along with a list of their accomplishments.

Yuri Gagarin:

As the first man to ever go into space, no list of famous astronauts would be complete without Yuri Gagarin. Born in the village of Klushino in the Smolensk Oblast on March 9th, 1934, Gagarin was drafted into the Soviet Air Force in 1955 and trained in the use of jet fighters. In 1960, he was selected alongside 19 other pilots to join the newly-formed Soviet Space Program.

Yury Gagarin before a space flight aboard the Vostok spacecraft. April 12, 1961 Credit: RIA Novosti
Yuri Gagarin before a space flight aboard the Vostok 1 spacecraft, April 12th, 1961. Credit: RIA Novosti

Gagarin was further selected to become part of the Sochi Six, an elite group of cosmonauts who formed the backbone of the Vostok program. Due to his training, physical size (as the spacecraft were quite cramped), and favor amongst his peers, Gagarin was selected to be the first human cosmonaut (they had already sent dogs) to make the journey.

On April 12th, 1961, Gagarin was launched aboard the Vostok 1 spacecraft from the Baikonur Cosmodrome, and thus became the fist man to go into space. During reentry, Gagarin claimed to have whistled “The Motherland Hears, The Motherland Knows”, and reportedly said, “I don’t see any God up here” when he reached suborbital altitude (which was falsely attributed).

Afterwards, he toured the world and became a celebrity at home, commemorated with stamps, statues, and the renaming of his ancestral village to Gagarin. The 12th of April is also known as “Cosmonauts Day” in Russia and many former Soviet-states in his honor.

Gagarin died during a routine training exercise in March 27th, 1968. The details of his death were not released until June of 2013, when a declassified report indicated that Gagarin’s death was caused by the error of another pilot.

Alan B. Shepard Jr.:

In addition to being an astronaut and one of the Mercury Seven – the first seven pilots selected by NASA to go into space – Shepard was also the first American man to go into space. He was born November 18th, 1923 in Pebble, California and graduated from the United States Naval Academy with a Bachelor of Science degree. While in the Navy, Shepard became a fighter pilot and served aboard several aircraft carriers in the Mediterranean.

Alan Shepard prepares for his historic flight on May 5, 1961. Credit: NASA
Alan Shepard prepares for his historic flight on May 5, 1961. Credit: NASA

In 1959, he was selected as one of 110 military test pilots to join NASA. As 0ne of the seven Mercury astronauts, Shepard was selected to be the first to go up on May 5th, 1961. Known as the Freedom 7 mission, this flight placed him into a suborbital flight around Earth. Unfortunately, Alan was beaten into space by Soviet cosmonaut Yuri Gagarin by only a few weeks, and hence became the first American to go into space.

Shepard went on to lead other missions, including the Apollo 14 mission – which was the third mission to land on the Moon. While on the lunar surface, he was photographed playing a round of golf and hit two balls across the surface. After leaving NASA, he became a successful businessman. He died of leukemia on July 21st, 1998, five weeks before the death of his wife of 53 years.

Valentina Tereshkova:

Another famous Russian cosmonaut, Tereshkova is also internationally renowned for being the first woman to go into space. Born in the village of Maslennikovo in central Russia on March 6th, 1937, Tereshkova became interested in parachuting from a young age and began training at the local aeroclub.

After Gagarin’s historic flight in 1961, the Soviets hopes to also be the first country to put a woman into space. On 16 February 1962, Valentina Tereshkova was selected to join the female cosmonaut corps, and was selected amongst hundreds to be one of five women who would go into space.

In addition to her expertise in parachuting (which was essential since Vostok pilots were to parachute from the capsule after reentry), her background as a “proletariat”, and the fact that her father was a war hero from the Russo-Finnish War, led to her being selected.

Soviet Cosmonaut Valentina Tereshkova photographed inside the Vostok-6 spacecraft on June 16, 1963. Credit: Roscosmos
Soviet Cosmonaut Valentina Tereshkova photographed inside the Vostok-6 spacecraft on June 16, 1963. Credit: Roscosmos

Her mission, Vostok 6, took place on June 16th, 1963. During her flight, Tereshkova orbited Earth forty-eight times, kept a flight log and took photographs that would prove useful to atmospheric studies. Aside from some nausea (which she later claimed was the result of spoiled food!) she maintained herself for the full three days and parachuted down during re-entry, landing a bit hard and bruising her face.

After returning home, Tereshkova went on to become a cosmonaut engineer and spent the rest of her life in key political positions. She married fellow cosmonaut Andrian Nikolayev and had a daughter. After her flight, the women’s corps was dissolved. Vostok 6 was to be the last of the Vostok flights, and it would be nineteen years before another woman would go into space (see Sally Ride, below).

John Glenn Jr.:

Colonel Glenn, USMC (retired) was a Marine Corps fighter pilot and a test pilot before becoming an astronaut. Due to his experience, he was chosen by NASA to be part of the Mercury Seven in 1959. On February 20, 1962, Glenn flew the Friendship 7 mission, and thus became the first American astronaut to orbit the Earth and the fifth person to go into space.

John Glenn enters his Friendship 7 spacecraft on On Feb. 20, 1962. Credit: NASA
John Glenn enters his Friendship 7 spacecraft on On Feb. 20, 1962. Credit: NASA

For his contributions to spaceflight, John Glenn earned the Space Congressional Medal of Honor. After an extensive career as an astronaut, Glenn retired from NASA on January 16th, 1964, to enter politics. He won his first bid to become a US Senator in 1974, representing Ohio for the Democratic Party, and was reelected numerous times before retiring in January of 1999.

With the death of Scott Carpenter on October 10, 2013, he became the last surviving member of the Mercury Seven. He was also the only astronaut to fly in both the Mercury and Space Shuttle programs – at age 77, he flew as a Payload Specialist on Discovery mission (STS-95). For his history of service, he was awarded the Presidential Medal of Freedom in 2012.

Neil Armstrong:

Neil Armstrong is arguably the most famous astronauts, and indeed one of the most famous people that has ever lived. As commander of the historic Apollo 11 mission, he will forever be remembered as the first man to ever walk on a body other than Earth. Born on August 5th, 1930, in Wapakoneta, Ohio, he graduated from Purdue University and served the National Advisory Committee for Aeronautics High-Speed Flight Station before becoming an astronaut.

Neil A. Armstrong inside the Lunar Module after EVA
Neil A. Armstrong inside the Lunar Module after EVA. Credit: NASA

In accordance with the Holloway Plan, Neil studied at Purdue for two years and then committed to three years of military service as a naval aviator before completing his degree. During this time, he trained in the use of jet aircraft and became a test pilot at Andrews Air Force base, meeting such personalities as Chuck Yeager.

In 1962, when NASA was looking to create a second group of astronauts (after the Mercury 7), Armstrong joined and became part of the Gemini program. He flew two missions, as the command pilot and back-up command pilot for Gemini 8 and Gemini 11 (both in 1966), before being offered a spot with the Apollo program.

On July 16th, 1969, Armstrong went into space aboard the Apollo 11 spacecraft, alongside “Buzz” Aldrin and Michael Collins. On the 20th, after the lunar module set down on the surface,  he became the first person to walk on the Moon.  As he stepped onto the lunar surface, Armstrong uttered the famous words, “That’s one small step for a man, one giant leap for mankind.”

After retiring from NASA in 1971, Armstrong completed his master’s degree in aerospace engineering, became a professor at the University of Cincinnati, and a private businessman.

On Augusts 25th, 2012, he died at the age of 82 after suffering complications from coronary artery bypass surgery. On September 14th, his cremated remains were scattered in the Atlantic Ocean during a burial-at-sea ceremony aboard the USS Philippine Sea.

For his accomplishments, Armstrong was awarded the Presidential Medal of Freedom, the Congressional Space Medal of Honor, and the Congressional Gold Medal in 2009.

James Lovell Jr.:

Lovell was born on March 25th, 1928 in Cleveland, Ohio. Like Shepard, he graduated from the US Naval Academy and served as a pilot before becoming one of the Mercury Seven. Over the course of his career, he flew several missions into space and served in multiple roles. The first was as the pilot of the Apollo 8 command module, which was the first spacecraft to enter lunar orbit.

He also served as backup commander during the Gemini 12 mission, which included a rendezvous with another manned spacecraft. However, he is most famous for his role as commander the Apollo 13 mission, which suffered a critical failure en route to the Moon but was brought back safely due to the efforts of her crew and the ground control team.

Lovell is a recipient of the Congressional Space Medal of Honor and the Presidential Medal of Freedom. He is one of only 24 people to have flown to the Moon, the first of only three people to fly to the Moon twice, and the only one to have flown there twice without making a landing. Lovell was also the first person to fly in space four times.

Original crew photo. Left to right: Lovell, Mattingly, Haise. Credit: NASA
Original crew photo, (left to right) Jim Lovell, Thomas K. Mattingly, and Fred W. Haise. Credit: NASA

Dr. Sally Ride:

Sally Ride became renowned in the 1980s for being one of the first women to go into space. Though Russians had already sent up two female astronauts – Valentina Tereshkova (1963) and Svetlana Savitskaya (1982) – Ride was the first American female astronaut to make the journey. Born on May 26th, 1951, in La Jolla, California, Ride received her doctorate from Stanford University before joining NASA in 1978.

On June 18th, 1983, she became the first American female astronaut to go into space as part of the STS-7 mission that flew aboard the space shuttle Challenger. While in orbit, the five-person crew deployed two communications satellites and Ride became the first woman to use the robot arm (aka. Canadarm).

Her second space flight was in 1984, also on board the Challenger. In 1986, Ride was named to the Rogers Commission, which was charged with investigating the space shuttle Challenger disaster. In 2003, she would serve on the committee investigating the space shuttle Columbia disaster, and was the only person to serve on both.

Sally Ride communicates with ground controllers from the flight deck during the six-day mission in Challenger, 1983. Credit: U.S. National Archives and Records Administration
Sally Ride communicates with ground controllers from the flight deck during STL-7 in 1983. Credit: U.S. National Archives and Records Administration

Ride retired from NASA in 1987 as a professor of physics and continued to teach until her death in 2012 from pancreatic cancer. For her service, she was given numerous awards, which included the National Space Society’s von Braun Award, two NASA Space Flight Medals, and was inducted into the National Women’s Hall of Fame and the Astronaut Hall of Fame.

Chris Hadfield:

Last, but certainly not least, there’s Chris Hadfield, the Canadian astronaut, pilot and engineer who became famous for his rendition of “Space Oddity” while serving as the commander of the International Space Station. Born on August 29th, 1959 in Sarnia, Ontario, Hadfield became interesting in flying at a young age and in becoming an astronaut when he watched the televised Apollo 11 landing at age nine.

After graduating from high school, Hadfield joined the Canadian Armed Forces and spent two years at Royal Roads Military College followed by two years at the Royal Military College, where he received a bachelor’s degree in mechanical engineering in 1982. He then became a fighter pilot with the Royal Canadian Air Force, flying missions for NORAD. He also flew as a test pilot out of Andrews Air Force Base as part of an officer exchange.

In 1992, Hadfield became part of the Canadian Space Agency and was assigned to NASA’s Johnson Space Center in Houston, as a technical and safety specialist for Shuttle Operations Development. He participated in two space missions – STS-74 and STS-100 in 1995 and 2001, respectively – as a Mission Specialist. These missions involved rendezvousing with Mir and the ISS.

Canadian astronaut Chris Hadfield, the first Canadian to serve as commander of the ISS. Credit: CTV
Canadian astronaut Chris Hadfield performing his rendition of “Space Oddity”. Hadfield is the first Canadian to serve as commander of the ISS. Credit: CTV

On December 19th 2012, Hadfield launched in the Soyuz TMA-07M flight for a long duration stay on board the ISS as part of Expedition 35. He became the first Canadian to command the ISS when the crew of Expedition 34 departed in March 2013, and received significant media exposure due to his extensive use of social media to promote space exploration.

Forbes described Hadfield as “perhaps the most social media savvy astronaut ever to leave Earth”. His promotional activities included a collaboration with Ed Robertson of The Barenaked Ladies and the Wexford Gleeks, singing “Is Somebody Singing?“ (I.S.S.) via Skype. The broadcast of this event was a major media sensation, as was his rendition of David Bowie’s “Space Oddity“, which he sung shortly before departing the station in May 2013.

For his service, Hadfield has received numerous honors, including the Order of Canada in 2014, the Vanier Award in 2001, NASA Exceptional Service Medal in 2002, the Queen’s Golden Jubilee Medal in 2002, and the Queen’s Diamond Jubilee Medal in 2012. He is also the only Canadian to have received both a military and civilian Meritorious Service Cross, the military medal in 2001 and the civilian one in 2013.

Universe Today has interesting articles on Neil Armstrong, “Buzz” Edwin Aldrin, and the enduring legacy of Apollo 11.

If you are looking for more information, you should check out famous aviators and astronauts and astronaut biographies.

Astronomy Cast has an episode on the US space shuttle.

Sources:
NASA: Alan Shepard Jr
NASA: Neil Armstrong
NASA: John Glenn
NASA: James Lovell Jr.
NASA: Sally Ride

Posted on by Matt Williams

How Can We Live on Mars?

The Dragn Crew capsule is more than a modernized Apollo capsule. It will land softly and at least on Earth will be reusable while Musk and SpaceX dream of landing Falcon Crew on Mars. (Photo Credits: SpaceX)

Why live on Earth when you can live on Mars? Well, strictly speaking, you can’t. Mars is a completely hostile environment to human life, combining extreme cold with an unbreathable atmosphere and intense radiation. And while it is understood that the planet once had an atmosphere and lots of water, that was billions of years ago!

And yet, if we want to expand into the Solar System, we’ll need to learn how to live on other planets. And Mars is prime real-estate, compared to a lot of other bodies. So despite it being a challenge, given the right methods and technology, it is possible we could one day live on Mars. Here’s how we’ll do it.

Reasons To Go:

Let’s face it, humanity wants (and needs) to go Mars, and for several reasons.  For one, there’s the spirit of exploration, setting foot on a new world and exploring the next great frontier – like the Apollo astronauts did in the late 60s and early 70s.

Artist illustration of a Mars Colony. Image credit: NASA
Artist illustration of a Mars Colony. Image credit: NASA

We also need to go there if we want to create a backup location for humanity, in the event that life on Earth becomes untenable due to things like Climate Change. We could also go there to search for additional resources like water, precious metals, or additional croplands in case we can no longer feed ourselves.

In that respect, Mars is the next, natural destination. There’s also a little local support, as Mars does provide us some raw materials. The regolith, the material which covers the surface, could be used to make concrete, and there are cave systems which could be converted into underground habitats to protect citizens from the radiation.

Elon Musk has stated that the goal of SpaceX is to help humans get to Mars, and they’re designing rockets, landers and equipment to support that. Musk would like to build a Mars colony with about 1 million people. Which is a good choice, as its probably the second most habitable place in our Solar System. Real estate should be pretty cheap, but the commute is a bit much.

And then there’s the great vistas to think about. Mars is beautiful, after a fashion. It looks like a nice desert planet with winds, clouds, and ancient river beds. But maybe, just maybe, the best reason to go there is because it’s hard! There’s something to be said about setting a goal and achieving it, especially when it requires so much hard work and sacrifice.

Reasons NOT To Go:

Yeah, Mars is pretty great… if you’re not made of meat and don’t need to breathe oxygen. Otherwise, it’s incredibly hostile. It’s not much more habitable than the cold vacuum of space. First, there’s no air on Mars. So if you were dropped on the surface, the view would be spectacular. Then you’d quickly pass out, and expire a couple minutes later from a lack of oxygen.

There’s also virtually no air pressure, and temperatures are incredibly cold. And of course, there’s the constant radiation streaming from space. You also might want to note that the soil is toxic, so using it for planting would first require that it be put through a decontamination process.

A post-processed mosaic of MSL Mastcam images from Sol 582 (NASA/JPL-Caltech/MSSS. Edit by Jason Major)
Afternoon on Mars (MSL Mastcam mosaic)(NASA/JPL-Caltech/MSSS. Edit by Jason Major)

Assuming we can deal with those issues, there’s also the major problem of having limited access to spare parts and medical supplies. You can’t just go down to the store when you’re on Mars if your kidney gives out or if your sonic screwdriver breaks.

There will need to be a constant stream of supplies coming from Earth until the Martian economy is built up enough to support itself. And shipping from Earth will be very expensive, which will mean long period between supply drops.

One more big unknown is what the low gravity will do to the human body over months and years. At 40% of Earth normal, the long-term effects are not something we currently have any information on. Will it shorten our lifespan or lengthen it? We just don’t know.

There’s a long list of these types of problems. If we intend to live on Mars, and stay there permanently, we’ll be leaning pretty hard on our technology to keep us alive, never mind making us comfortable!

Possible Solutions:

In order to survive the lack of air pressure and the cold, humans will need pressurized and heated habitats. Martians, the terrestrial kind, will also need a spacesuit whenever they go outside. Every hour they spend outside will add to their radiation exposure, not to mention all the complications that exposure to radiation brings.

Artist's concept of a habitat for a Mars colony. Credit: NASA
Artist’s concept of a habitat for a Mars colony. Credit: NASA

For the long term, we’ll need to figure out how to extract water from underground supplies, and use that to generate breathable air and rocket fuel. And once we’ve reduced the risk of suffocation or dying of dehydration, we’ll need to consider food sources, as we’ll be outside the delivery area of everyone except Planet Express. Care packages could be shipped up from Earth, but that’s going to come with a hefty price tag.

We’ll need to produce our own food too, since we can’t possible hope to ship it all in on a regular basis. Interestingly, although toxic, Martian soil can be used to grow plants once you supplement it and remove some of the harsher chemicals. NASA’s extensive experience in hydroponics will help.

To thrive on Mars, the brave adventurers may want to change themselves, or possibly their offspring. This could lead to genetic engineering to help future generations adapt to the low gravity, higher radiation and lower air pressure. And why stop at humans? Human colonists could also adapt their plants and animals to live there as well.

Finally, to take things to the next level, humanity could make a few planetary renovations. Basically, we could change Mars itself through the process of terraforming. To do this, we’ll need to release megatons of greenhouse gasses to warm the planet, unleashing the frozen water reserves. Perhaps we’ll crash a few hundred comets into the planet to deliver water and other chemicals too.

An artist's conception of future Mars astronauts. Credit: NASA/JPL-Caltech
An artist’s conception of future Mars astronauts. Credit: NASA/JPL-Caltech

This might take thousands, or even millions of years. And the price tag will be, for lack of a better word, astronomical! Still, the technology required to do all this is within our current means, and the process could restore Mars to a place where we could live on it even without a spacesuit.

And even though we may not have all the particulars worked out just yet, there is something to be said about a challenge. As history has shown, there is little better than a seemingly insurmountable challenge to bring out the best in all of us, and to make what seems like an impossible dream a reality.

To quote the late, great John F. Kennedy, who addressed the people of the United States back when they was embarking on a similarly difficult mission:

We choose to go to the Moon! … We choose to go to the Moon in this decade and do the other things, not because they are easy, but because they are hard; because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one we intend to win

What do you think? Would you be part of the Mars terraforming expedition? Tell us in the comments below.

We have written many interesting articles about Mars here at Universe Today. Here’s How Do We Colonize Mars?, Mars Colony Will Have to Wait, Solar Power is Best for Mars Colonies, and Elon Musk is Sending Humans to Mars in 2024.

For more information, check out NASA’s Journey to Mars, and NASA Quest’s Mars Colony Project.

Astronomy Cast also has episodes on the subject, like Episode 52: Mars, and Episode 95: Humans to Mars, Part 2: Colonists.

Posted on by Matt Williams

What are the Longest Rivers In the World?

The Nile River and Delta, viewed at night by the Expedition 25 crew on Oct. 28, 2010. Credit: NASA

There are many long rivers in the world, but which ones are the longest? Naturally, there is a disagreement over the answer to this question. While The Nile has traditionally been considered to be longest in the world, the Amazon has some pretty fierce defenders as well. The debate arises over the difficulty in determining the full extent of a river, and also because measurements differ according to who measured them.

Another source of disagreement is the role played by tributaries, with some scientists arguing for their inclusion while others leave them out. Luckily, when determining length, several major rivers stand out from the crowd. Here are a few, and the reasons for why they made the list:

Definition:
There are many factors in determining the precise length of a river. These include the source, the identification (or the definition) of the river’s mouth, and the scale of measurement when determining the river length between source and mouth. As a result, the length measurements of many rivers are only approximations.

A river’s “true source” is considered to be the source of whichever tributary is farthest from the mouth, but this tributary may or may not have the same name as the main stem river. Furthermore, it is sometimes hard to state exactly where a river begins – especially rivers that are formed by ephemeral streams, swamps, or changing lakes.

Nile Delta from space by the MODIS sensor on the Terra satellite. Credit: Jacques Descloitres/NASA/GSFC
Nile Delta from space by the MODIS sensor on the Terra satellite. Credit: Jacques Descloitres/NASA/GSFC

The mouth of a river is hard to determine in cases where the river has a large estuary that gradually widens and opens into the ocean. Some rivers do not have a mouth, and instead dwindle to very low water volume and disappear underground. A river may also have multiple channels, or anabranches, and it may not be clear how to measure the length through a lake.

Seasonal and annual changes may alter rivers as well, not to mention cycles of erosion and flooding, dams, levees, and geological engineering. In addition, the length of meanders can change significantly over time when a new channel cuts across a narrow strip of land, bypassing a large river bend.

The Nile:
The Nile River, located in Africa, is listed as being 6,853 kilometers (4,258 miles) long, and is hence commonly considered to be the longest river in the world. This river and its water resources are shared by eleven countries – Tanzania, Uganda, Rwanda, Burundi, Congo-Kinshasa, Kenya, Ethiopia, Eritrea, South Sudan, the Sudan and Egypt.

In ancient times, its existence was closely tied to the rise of civilization in the Near East, being the main source of irrigation and fresh water for multiple Egyptian dynasties. Today, it remains the primary water source for both Egypt and the Sudan.

Lake Victoria, as viewed by the Moderate Resolution Imaging Spectroradiometer (MODIS) o
Lake Victoria, as viewed by the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra satellite. Credit: NASA/EO

The source of the Nile is traditionally considered to be Lake Victoria, but Victoria itself has feeder rivers of considerable size. It’s two main tributaries,  are the White Nile and Blue Nile. The former is considered to be the headwaters and primary stream of the Nile itself, but the latter is the primary source of water and silt.

The Amazon:
The Amazon River is the longest river in South America, and the largest river in the world in terms of water discharge. This river has a series of major river systems in Colombia, Ecuador and Peru. At roughly 6,437 km (4,000 mi) in length, it is also considered to be the second-longest river in the world.

However, Brazilian scientists claimed to have found the most distant source of the Amazon in the Andes. This source is apparently a glacial stream emanating from the peak of Nevado Mismi in the Peruvian Andes, roughly 700 km (430 mi) southeast of Lima. If this is correct, then the Amazon is in fact 6.800 kilometers (4,225 miles) long, making it the world’s longest.

Satellite image of a flooded section of the Amazon river. Credit: NASA
Satellite image of a flooded section of the Amazon river. Credit: NASA

The Yangtze:
The third longest river in the world is the Yangtze – or as it’s known in China, the Chang Jiang River. The Yangtze is 6,380 kilometers (3,964 miles) in length, making it the longest river in Asia. It originates from the glaciers of the Qinghai-Tibet Plateau in Qinghai province, flows eastward across southwest, central and eastern China, and then empties into the East China Sea at Shanghai.

The Yangtze River has played a large role in the history, culture and economy of China, and continues to do so to this day. In addition to running through multiple ecosystems in China, its existence was also pivotal to human settlement, the development of agriculture, and the rise of civilization in East Asia.

Today, the prosperous Yangtze River Delta generates as much as 20% of China’s Gross Domestic Product (GDP), and the Three Gorges Dam – located on the Yangtze River near the town of Sandouping – is the largest hydro-electric power station in the world. Because of the impact of human infrastructure, some sections of the river are now protected wildlife preserves.

The first turn of the Yangtze at Shigu (??) in Yunnan Province, where the river turns 180 degrees from south- to north-bound. Credit: peace-on-earth.org/Jialiang Gao
The first turn of the Yangtze in Yunnan Province, where the river turns 180 degrees from south- to north-bound. Credit: peace-on-earth.org/Jialiang Gao

The Mississippi-Missouri-Jefferson:
At 6,275 kilometers (3,902 miles) the Mississippi-Missouri-Jefferson River system is the fourth longest in the world and the longest river in the United States. Although each river separately would not be in the top five, these three rivers are grouped together into one because the Missouri River meets the Mississippi near the city of St. Louis, while the Missouri connects to the Jefferson river in Montana.

However, the main thrust of the Mississippi runs north-south, rising in northern Minnesota and meandering slowly southwards for 3,730 km (2,320 miles) before reaching the Mississippi River Delta at the Gulf of Mexico.

With its many tributaries, the Mississippi’s watershed drains all or parts of 31 U.S. states and 2 Canadian provinces between the Rocky and Appalachian Mountains. It also borders and/or passes through the states of Minnesota, Wisconsin, Iowa, Illinois, Missouri, Kentucky, Tennessee, Arkansas, Mississippi, and Louisiana.

The Mississippi River and its tributaries have a long history of significance to Native American cultures. Many nations lived along its river banks, most of which were hunters and gathers who used the river as a source of water and for transportation. But for some – such as the Mound builders – the river was key to the formation of prolific agricultural societies.

The Mississippi River Delta. Credit: ESA
The Mississippi River Delta shown draining into the Gulf of Mexico from space. Credit: ESA

The arrival of Europeans in the 1500s changed the native way of life drastically as first explorers, then settlers, ventured into the basin in increasing numbers and colonized the area. Initially a barrier between New Spain, New France, and the Thirteen Colonies, it grew to become a major artery of transportation and western expansion for the United States by the 19th century.

The Yellow River:
Huang He, which is also known as the Yellow River because of the color of its silt, is the third longest river in Asia and the sixth longest river in the world. Located in China and measuring 5,464 kilometers (3,395 miles) in length, the river originates the Bayan Har Mountains in Qinghai province, western China. It then flows through nine provinces before emptying into the Bohai Sea near the city of Dongying in Shandong province.

The Yellow River is also known as “the cradle of Chinese civilization” because of the pivotal role it played in the development of Chinese culture. Much like the Yangtze, the presence of human settlements dates back to the Paleolithic Era, and the fertile flood basins contributed to the rise of agricultural communities which eventually integrated with the less-developed settlements along the southern Yangtze.

Before modern dams became an option, the Yellow River was extremely prone to flooding. In the roughly 2,540 years before 1946 CE, the Yellow River is believed to have flooded 1,593 times and shifted its course many times (sometimes severely). These floods include some of the deadliest natural disasters ever recorded, thus earning the river the nicknames “China’s Sorrow” and “Scourge of the Sons of Han.”

China's Yellow River Delta. Credit: NASA/EO
China’s Yellow River Delta, as seen from space in 2009. Credit: NASA/EO

The Congo-Chambeshi:
At 4,700 km (2,920 miles), the Congo River (aka. Zaire River) in Africa is the ninth longest river in the world. Interestingly enough, it is also its deepest – with measured depths exceeding 220 m (720 ft) – and the second largest river in the world in terms of discharge (after the Amazon).

Originating deep in the eastern region of the Democratic Republic of Congo (DRC, formerly Zaire), the Congo is fed by the Lualaba river, which is itself fed by the Luyua and Luapula rivers that are connected to Lake Mweru and Lake Bangwelo. The river then runs west and constitutes much of the border between the DRC and its eastern neighbor, the Republic of Congo.

The Congo river gets its name from the Kingdom of Kongo which was situated on the left banks of the river estuary. The kingdom is in turn named for its Bantu population, which were described in 17th century European records as Esikongo. The name Zaire is from a Portuguese adaptation of a Kikongo word nzere (“river”), a truncation of nzadi o nzere (“river swallowing rivers”).

Envisat image, acquired on 14 January 2009, features the Congo River Basin’s rainforests. Credit: ESA
The Congo River and rainforest, as acquired on Jan 14th, 2009 by the ESA’s Envisat satellite. Credit: ESA

The river was known as Zaire during the 16th and 17th centuries, but the word Congo has since replaced Zaire gradually in English usage. However, references to Zahir or Zaire, as the name used by the natives (i.e. derived from Portuguese usage), has remained common throughout this same period.

All the states that have existed in the region since attaining their independence from Belgium in 1960 – the DRC (which was named Zaire from 1971-1997) and the Republic of Congo – in turn derive their names from the river.

And those are just some of the longest rivers in the world! If you’re interested, Universe Today has many articles on rivers, such as what is the world’s widest river?

For more information, check out longest rivers in the world and Amazon longer than the Nile. Astronomy Cast also has an episode on Earth which addresses rivers.

Sources:
Google Book: Seven Natural Wonders of Central and South America
The Nature Conservancy
About.com: Geography
How Stuff Works
About.com – Longest Rivers
Louisiana State University
New World Encyclopedia

Posted on by Matt Williams

What is a Hunter’s Moon?

A full moon in October is known as a "Hunters Moon". Credit: David Haworth/stargazing.net

If you live in the northern hemisphere, than stargazing during the early autumn months can a bit tricky. During certain times in these seasons, the stars, planets and Milky Way will be obscured by the presence of some very beautiful full moons. But if you’re a fan of moongazing, then you’re in luck.

Because it is also around this time (the month of October) that people looking to the night sky will have the chance to see what is known as a Hunter’s Moon. A slight variation on a full moon, the Hunter’s Moon has long been regarded as a significant event in traditional folklore, and a subject of interest for astronomers.

Definition:

Also known as a sanguine or “blood” moon, the term “Hunters Moon” is used traditionally to refer to a full moon that appears during the month of October. It is preceded by the appearance of a “Harvest Moon”, which is the full moon closest to the autumnal equinox (which falls on the 22nd or 23rd of September).

The Hunter’s Moon typically appears in October, except once every four years when it doesn’t appear until November. The name dates back to the First Nations of North America. It is so-called because it was during the month of October, when the deers had fatted themselves over the course of the summer, that hunters tracked and killed prey by autumn moonlight, stockpiling food for the coming winter.

Full Moon Rising Over Northwest Georgia on June 22nd, 2013. Credit and copyright: Stephen Rahn.
Full Moon Rising Over Northwest Georgia on June 22nd, 2013. Credit and copyright: Stephen Rahn.

Characteristics:

Although typically the Moon rises 50 minutes later each day, things are different for the Hunter’s Moon (as well as the Harvest Moon). Both of these moons usually rise 30 minutes later on each successive night, which means that sunset and moonrise are not far apart.

This means there is prolonged periods of light during this time of the the year, which is the reason why these moons have traditionally been used by hunters and farmers to finish their work.

This difference between the timing of the sunset and moonrise is due to its orbit, meaning that the angle the Moon makes with the horizon is narrower during this time of year. The Hunter’s Moon is generally not bigger or brighter than any of the other full moons. Thus, the only difference between it and other full moons is the that the time between sunset and moonrise is shorter.

History of Observation:

Because the approach of winter signaled the possibility of going hungry in pre-Industrial times, the Hunter’s Moon was generally accorded with special honor, historically serving as an important feast day in both northern Europe and among many Native American tribes.

Traditionally, Native American hunters used the full moon of October to stalk deer and to spot foxes at night as they prepared for the coming winter. Because the fields were traditionally reaped in late September or early October, hunters could easily see foxes and other animals that came out to glean from the fallen grains.

The Hunter’s Moon is accorded similar significance in Europe, where it was also seen as a prime time to hunt during the post-harvest, pre-winter period when conditions were optimal for spotting prey. However, the term did not enter into usage for Europeans until after they made contact with Indigenous Americans and began colonizing North America.

The first recorded mentions of a “Hunter’s Moon” began in the early 18th century. The entry in the Oxford English Dictionary for “Hunter’s Moon” cites a 1710 edition of The British Apollo, where the term is attributed to “the country people”. The names are now referred to regularly by American sources, where they are often popularly attributed to “the Native Americans”.

In India, the harvest festival of Sharad Purnima, which marks the end of the monsoon season, is celebrated on the full moon day of the lunar month of Ashvin (September-October). There is a traditional celebration of the moon during this time that is known as the “Kaumudi” celebration – which translated, means “moonlight”.

The harvest festival of Shrad Purnima is celebrated on the full moon day of the Hindu lunar month of Ashvin. Credit: http://dfwhindutemple.org
The harvest festival of Shrad Purnima is celebrated on the full moon day of the Hindu lunar month of Ashvin. Credit: dfwhindutemple.org

Interesting Facts:

Sometimes, the Harvest Moon is mistaken for the Hunter’s Moon because once every four years or so the Harvest Moon is in October instead of September.  When that happens, the Hunter’s Moon is in November. Traditionally, each month’s full moon has been given a name, although these names differ according to the source.

Other full moons of interest include the Wolf Moon in January, the Strawberry Moon in June, the Sturgeon Moon in August, the Cold Moon in December, and the Pink Moon in April. All of the full moons have different characteristics due to the location of the ecliptic – i.e. the path of the Sun – at the time of each.

The Hunter’s Moon is also associated with feasting. In the Northern Hemisphere, some Native American tribes and some places in Western Europe held a feast day. This feast day, the Feast of the Hunter’s Moon, was not been held since the 1700’s. However, the Feast of the Hunters’ Moon is a yearly festival in Lafayette, Indiana, which has been held in late September or early October every year since 1968.

We have many interesting articles about the moon here at Universe Today. For example, here are some about the red moon and a rundown of what a full moon is all about.

For more information, check out the page on the Hunter’s Moon at NightSkyInfo, and full moon names and meanings, courtesy of the Farmer’s Almanac.

Astronomy Cast has an interesting episode on the subject – Episode 113: The Moon: Part I

Sources:

Posted on by Nancy Atkinson

What Is The Difference Between Asteroids and Meteorites?

Various meteorites from 2008 TC3. Credit: P. Jenniskens, et. al. Click image for full description

Asteroids, meteors, and meteorites … It might be fair to say these rocks from space inspire both wonder and fear among us Earthlings. But knowing a bit more about each of them and how they differ may eliminate some potential misgivings. While all these rocks originate from space, they have different names depending their location — i.e. whether they are hurtling through space or hurtling through the atmosphere and impacting Earth’s surface.

In simplest terms here are the definitions:

Asteroid: a large rocky body in space, in orbit around the Sun.

Meteoroid: much smaller rocks or particles in orbit around the Sun.

Meteor: If a meteoroid enters the Earth’s atmosphere and vaporizes, it becomes a meteor, which is often called a shooting star.

Meteorite: If a small asteroid or large meteoroid survives its fiery passage through the Earth’s atmosphere and lands on Earth’s surface, it is then called a meteorite.

Another related term is bolide, which is a very bright meteor that often explodes in the atmosphere. This can also be called a fireball.

Let’s look at each in more detail:

Asteroids

An artists impression of an asteroid belt. Credit: NASA
An artists impression of an asteroid belt. Credit: NASA

Asteroids are found mainly in the asteroid belt, between Mars and Jupiter. Sometimes their orbits get perturbed or altered and some asteroids end up coming closer to the Sun, and therefore closer to Earth. In addition to the asteroid belt, however, there have been recent discussions among astronomers about the potential existence of large number asteroids in the Kuiper Belt and Oort Cloud. You can read a paper about this concept here, and a good article discussing the topic here.

The asteroid Vesta as seen by the Dawn spacecraft. Credit: NASA/JPL-Caltech/UCAL/MPS/DLR/IDA
The asteroid Vesta as seen by the Dawn spacecraft. Credit: NASA/JPL-Caltech/UCAL/MPS/DLR/IDA

Asteroids are sometimes referred to as minor planets or planetoids, but in general, they are rocky bodies that do not have an atmosphere. However, a few have their own moons. Our Solar System contains millions of asteroids, many of which are thought to be the shattered remnants of planetesimals – bodies within the young Sun’s solar nebula that never grew large enough to become planets.

The size of what classifies as an asteroid is not extremely well defined, as an asteroid can range from a few meters wide – like a boulder — to objects that are hundreds of kilometers in diameter. The largest asteroid is asteroid Ceres at about 952 km (592 miles) in diameter, and Ceres is so large that it is also categorized as a dwarf planet.

Most asteroids are made of rock, but as we explore and learn more about them we know that some are composed of metal, mostly nickel and iron. According to NASA, a small portion of the asteroid population may be burned-out comets whose ices have evaporated away and been blown off into space. Recently, astronomers have discovered some asteroids that mimic comets in that gas and dust are emanating from them, and as we mentioned earlier, there appears to be a large number of bodies with asteroid-like compositions but comet-like orbits.

How Often Do Asteroids Hit Earth?

Meteor Crater near Winslow, Arizona. Image credit: NASA.
Meteor Crater near Winslow, Arizona. Image credit: NASA.

While we know that some asteroids pass very close to Earth’s orbit around the Sun, we’ve been lucky in the history of humanity that we haven’t had a large asteroid hit Earth in the past several thousand years. It wasn’t until satellite imagery of Earth became widely available that scientists were able to see evidence of past asteroid impacts.

One of the more famous impact craters on Earth is Meteor Crater in Arizona in the US, which was made by an impact about 50,000 years ago. But there are about 175 known impact around the world – a few are quite large, like Vredefort Crater in South Africa which has an estimated radius of 190 kilometers (118 miles), making it the world’s largest known impact structure on Earth. Another notable impact site is off the coast of the Yucatan Peninsula in Mexico, and is believed to be a record of the event that led to the extinction of the dinosaurs 65 million years ago. You can see images of some of the most impressive Earth impact craters here.

These days, asteroid impacts are less of a threat. NASA estimates that about once a year an automobile-sized asteroid enters Earth’s atmosphere, creates an impressive fireball and disintegrates before ever reaching the surface. Studies of Earth’s history indicate that about once every 5,000 years or so on average an object the size of a football field hits Earth and causes significant damage. Once every few million years on average an object large enough to cause regional or global disaster impacts Earth. You can find more information about the frequency of impacts in this article from NASA.


Meteors, Meteoroids and Bolides

A bright meteor from September 21, 1994. Credit: John Chumack.
A bright meteor from September 21, 1994. Credit: John Chumack.

Space debris smaller than an asteroid are called meteoroids. A meteoroid is a piece of interplanetary matter that is smaller than an asteroid and frequently are only millimeters in size. Most meteoroids that enter the Earth’s atmosphere are so small that they vaporize completely and never reach the planet’s surface. When they burn up during their descent, they create a beautiful trail of light known as a meteor, sometimes called a shooting star.

Mostly these are harmless, but larger meteors that explode in the atmosphere – sometimes called bolides — can create shockwaves, which can cause problems. In February 2013 a meteor that exploded over Chelyabinsk, Russia shattered windows with its air blast. This meteoroid or bolide was estimated to be 18 meters (59 feet) in diameter. In 1908, a rocky meteoroid less than 100 meters in diameter is believed to have entered the atmosphere over the Tunguska region of Siberia in 1908 and the resulting shockwave knocked down trees for hundreds of square kilometers

How often is Earth hit by meteroids?

Chelyabinsk fireball recorded by a dashcam from Kamensk-Uralsky north of Chelyabinsk where it was still dawn.
Chelyabinsk fireball recorded by a dashcam from Kamensk-Uralsky north of Chelyabinsk where it was still dawn.

Because of the Chelyabinsk meteor in 2013, astronomers have acquired more information about the frequency of larger meteors that hit Earth, and there is now a growing consensus that the Earth gets hit by bigger space rocks more often than we previously thought. You can read more about that concept here.

This video from the B612 Foundation shows a visualization of the location of 26 space rocks that hit Earth between 2000 and 2013, each releasing energy equivalent to some of our most powerful nuclear weapons. The B612 foundation says that a Hiroshima-scale asteroid explosion happens in our atmosphere on average once a year, but many are not detected because they explode high in the atmosphere, or because most of the Earth’s surface is water and even a large percentage of land is fairly uninhabited by humans.

Estimates vary of how much cosmic dust and meteors enter Earth’s atmosphere each day, but range anywhere from 5 to 300 metric tons. Satellite observations suggest that 100-300 metric tons of cosmic dust enter the atmosphere each day. This figure comes from the rate of accumulation in polar ice cores and deep-sea sediments of rare elements linked to cosmic dust, such as iridium and osmium.

But other measurements – which includes meteor radar observations, laser observations and measurements by high altitude aircraft — indicate that the input could be as low as 5 metric ton per day. Read more about this here.

For a documented list of bolide events, you can check out this page from JPL.

Meteorite

A stunning slice of the Glorieta pallasite meteorite cut thin enough to allow light to shine through its many olivine crystals. Credit: Mike Miller
A stunning slice of the Glorieta pallasite meteorite cut thin enough to allow light to shine through its many olivine crystals. Credit: Mike Miller

If any part of a meteoroid survives the fall through the atmosphere and lands on Earth, it is called a meteorite. Although the vast majority of meteorites are very small, their size can range from about a fraction of a gram (the size of a pebble) to 100 kilograms (220 lbs) or more (the size of a huge, life-destroying boulder). Meteorites smaller than 2mm are classified as micrometeorites.

Meteorites have traditionally been divided into three broad categories, depending on their structure, chemical and isotopic composition and mineralogy. Stony meteorites are rocks, mainly composed of silicate minerals; iron meteorites that are largely composed of metallic iron-nickel; and, stony-iron meteorites that contain large amounts of both metallic and rocky material.

Meteorites have also been found on the Moon and Mars and conversely, scientists have traced the origination of the meteorites found here on Earth to four other bodies: the Moon, Mars, the asteroid 4 Vesta, and the comet Wild 2. Meteorites are the source of a great deal of the knowledge that we have have about the composition of other celestial bodies.

How Often Do Meteorites Hit Earth?

On Feb. 28, 2009, Peter Jenniskens (SETI/NASA), finds his first 2008TC3 meteorite after an 18-mile long journey. "It was an incredible feeling," Jenniskens said. The African Nubian Desert meteorite of Oct 7, 2008 was the first asteroid whose impact with Earth was predicted while still in space approaching Earth. 2008TC3 and Chelyabinsk are part of the released data set. (Credit: NASA/SETI/P.Jenniskens)
On Feb. 28, 2009, Peter Jenniskens (SETI/NASA), finds his first 2008TC3 meteorite after an 18-mile long journey. “It was an incredible feeling,” Jenniskens said. The African Nubian Desert meteorite of Oct 7, 2008 was the first asteroid whose impact with Earth was predicted while still in space approaching Earth. 2008TC3 and Chelyabinsk are part of the released data set. (Credit: NASA/SETI/P.Jenniskens)

According to the Planetary Science Institute, it is estimated that probably 500 meteorites reach the surface of the Earth each year, but less than 10 are recovered. This is because most fall into water (oceans, seas or lakes) or land in remote areas of the Earth that are not accessible, or are just not seen to fall.

You can read more about meteorites that were found from the Chelyabinsk meteor here.

Summary

In short, the difference between asteroids and meteors all comes down to a question of location. Asteroids are always found in space. Once it enters an atmosphere, it becomes a meteor, and then a meteorite after it hits the ground. Each are made of the same basic materials – minerals and rock – and each originated in space. The main difference is where they are when they are being observed.

We have many great articles on the subject of asteroids and meteorites here at Universe Today, such as this general information article on asteroids, this article and infographic about the difference between comets, asteroids and meteors, and these articles that deal with Ceres and Vesta. And here are some recent articles about the Chelyabinsk meteor that landed in Russia, as well as a 2 billion-year old Martian meteorite that contains evidence of water on Mars.

There is some good information on a NASA page as well as some great information here on Universe Today and Astronomy Cast.

Sources:
JPL’s Near Earth Asteroid Office
Planetary Science Institute
NASA: Asteroids
NASA: Meteors

Posted on by Fraser Cain

Would We See the Aliens Coming?

Would We See the Aliens Coming?

If aliens were heading towards the Earth, would we see them coming?

Classic sci fi trope time. The air force detects a fleet of alien spacecraft out past Jupiter, leaving enough time to panic and demonstrate what awful monsters we truly are before they come ring our bell.
Is that how this would work?

Imagine a pivotal scene in your favorite alien mega disaster movie. Like the one where the gigantic alien ships appear over London, Washington, Tokyo, and Paris and shoots its light-explody ray, obliterating a montage of iconic buildings. Demonstrating how our landmark construction technology is nothing against their superior firepower.

What could we do? We’re merely meat muppets with pitiful silicon based technology. How could we ever hope to detect these aliens with their stealth spacecraft and 3rd stage guild navigators? If we’re going to do this, I’m going to make up some rules. If you don’t like my rules, go get your own show and then you can have your own rules.

Alternately, as some of you are clearly aware, you can rail against the Guide To Space in the comments below. Dune reference notwithstanding, I’m going to assume that aliens live in our Universe and obey the laws of physics as we understand them. And I know you’re going to say, what if they use physics we haven’t discovered yet?

Then just pause this video and get that out of your system. You can make that your first decree against the state right in the comments below. As I was saying, physical aliens, physical universe. We’ll discuss the metaphysical aliens in a magic universe in a future video. The ones that have crystals and can heal your liver through the power of song.

A basic rule of the Universe is that you can’t go faster than the speed of light. So I’m going to have any aliens trying to attack us traveling at sublight speeds.

So, we’ll say they’ve got access to a giant mountain of power. They can afford to travel at 10% the speed of light, which means before they get to us, they have to slow down. At this speed, deceleration is expensive. We’d see the energy signature from their brakes long before they even reached Earth.

Let’s say they’re passing the orbit of the dwarf planet Pluto, which is 4 light-hours away. Since they’re travelling at 10% the speed of light, we’d have about 40 hours to scramble jet fighters, get those tanks out onto the streets and round up Will Smith, Jeff Goldblum and Bruce Willis to hide behind.

A composite image with Chandra data (purple) showing a "point-like source" beside the remains of a supernova, suggesting a companion star may have survived the explosion. Credit: X-ray: NASA/CXC/SAO/F.Seward et al; Optical: NOAO/CTIO/MCELS, DSS
A composite image with Chandra data (purple) showing a “point-like source” beside the remains of a supernova, suggesting a companion star may have survived the explosion. Credit: X-ray: NASA/CXC/SAO/F.Seward et al; Optical: NOAO/CTIO/MCELS, DSS

Would we even notice? Maybe, or maybe not. A growing trend in astronomy is scanning the sky on a regular basis, looking for changes. Changes like supernova explosions, asteroids and comets zipping past, and pulsating variable stars.

One of the most exciting new observatories under construction is the Large Synoptic Survey Telescope in Chile. Once it begins regular operations in 2022, this array of telescopes will photograph the entire sky in fairly high resolution every few nights.

Computers will process the torrent of data coming from the observatory and search for anything that changes. What if they engage their cloak?

Actually (push glasses up your nose) the laws of physics say that the aliens can’t hide the waste heat from whatever space drive they’re using. We’re actually pretty good at detecting heat with our infrared telescopes.

A space drive decelerating a city-sized alien spacecraft from a significant portion of the speed of light would shed a mountain of heat, and that’s all heat we might detect.

Astronomers have been searching for alien civilizations by looking for waste heat generated by Dyson spheres encapsulating entire stars or even all the stars in a galaxy. Nothing’s turned up yet. Which I for one, find a little suspicious.

Freemon Dyson theorized that eventually, a civilization would be able to build a megastructure around its star to capture all its energy. Credit: SentientDevelopments.com
Freemon Dyson theorized that eventually, a civilization would be able to build a megastructure around its star to capture all its energy. Credit: SentientDevelopments.com

If you’re from an alien race who’s planning to invade. Cover your ears. If aliens wanted to catch us off guard, they can use one of the oldest tricks in the aerial combat book, known as the Dicta Boelcke. They can fly at us using the Sun as camouflage. A rather large portion of the sky is completely obscured by that glowing ball of fiery plasma. It worked in WW1, and it’ll still work now.

Okay, aliens you can listen in again. Everyone else might want to mute the next part, as it’s not terribly reassuring. Astronomers often discover asteroids skimming by the Earth just after they’ve just gone past. That’s because they hurl at us from the Sun, just like clever aliens.

To spot those asteroids, we’ll need to deploy a space-based sky survey that can watch the heavens from a different perspective than Earth. Plans for this kind of mission are actually in the works.

Even with our rudimentary technology, we’d actually stand a pretty good chance of noticing the alien attack vessels before they actually arrived at centre of Sector 001. It’ll get better with automated observatories and space-based sky surveys.

Of course, there’s little we can do if we did know the aliens were coming. We’d be best to start with some kind of deterrent, contaminate all our fresh water, load our livestock up on antibiotics and cover our cities in toxic smog to deter the harvesting of our citizens.

Do you think we’d stand a chance against an alien invasion? Tell us how we’d do in the comments below.

Posted on by Matt Williams

How Do We Settle on Mars?

Artist's illustration of a SpaceX Starship lands on Mars. Credit: SpaceX

Welcome back to our series on Settling the Solar System! Today, we take a look at that cold and dry world known as “Earth’s Twin”. I’m talking about Mars. Enjoy!

Mars. It’s a pretty unforgiving place. On this dry, desiccated world, the average surface temperature is -55 °C (-67 °F). And at the poles, temperatures can reach as low as  -153 °C (243 °F). Much of that has to do with its thin atmosphere, which is too thin to retain heat (not to mention breathe). So why then is the idea of colonizing Mars so intriguing to us?

Well, there are a number of reasons, which include the similarities between our two planets, the availability of water, the prospects for generating food, oxygen, and building materials on-site. And there are even long-term benefits to using Mars as a source of raw materials and terraforming it into a liveable environment. Let’s go over them one by one…

Examples in Fiction:

The idea of exploring and settling Mars has been explored in fiction for over a century. Most of the earliest depiction of Mars in fiction involved a planet with canals, vegetation, and indigenous life – owing to the observations of the astronomers like Giovanni Schiaparelli and Percival Lowell.

However, by the latter half of the 20th century (thanks in large part to the Mariner 4 missions and scientists learning of the true conditions on Mars) fictional accounts moved away from the idea of a Martian civilization and began to deal with humans eventually colonizing and transforming the environment to suit their needs.

Artist impression of a Mars settlement with cutaway view. Credit: NASA Ames Research Center
Artist impression of a Mars settlement with cutaway view. Credit: NASA Ames Research Center

This shift is perhaps best illustrated by Ray Bradbury’s The Martian Chronicles (published in 1950). A series of short stories that take place predominantly on Mars, the collection begins with stories about a Martian civilization that begins to encounter human explorers. The stories then transition to ones that deal with human settlements on the planet, the genocide of the Martians, and Earth eventually experiencing nuclear war.

During the 1950s, many classic science fiction authors wrote about colonizing Mars. These included Arthur C. Clarke and his 1951 story The Sands of Mars, which is told from the point of view of a human reporter who travels to Mars to write about human colonists. While attempting to make a life for themselves on a desert planet, they discover that Mars has native life forms.

In 1952, Isaac Asimov released The Martian Way, a story that deals with the conflict between Earth and Mars colonists. The latter manage to survive by salvaging space junk and are forced to travel to Saturn to harvest ice when Earth enforces an embargo on their planet.

Robert A. Heinlein’s seminal novel Stranger in a Strange Land (1961) tells the story of a human who was raised on Mars by the native Martians and then travels to Earth as a young adult. His contact with humans proves to have a profound effect on Earth’s culture, and calls into questions many of the social mores and accepted norms of Heinlein’s time.

Artist's concept of possible exploration of the surface of Mars. Credit: NASA Ames Research Center
Artist’s concept of possible exploration of the surface of Mars. Credit: NASA Ames Research Center

Philip K. Dick’s fiction also features Mars often, in every case being a dry, empty land with no native inhabitants. In his works Martian Time Slip (1964), and The Three Stigmata of Palmer Eldritch (1965), life on Mars is presented as difficult, consisting of isolated communities who do not want to live there.

In Do Androids Dream of Electric Sheep? (1968), most of humanity has left Earth after a nuclear war and now live in “the colonies” on Mars. Androids (Replicants) escaping illegally to come back to Earth claim that they have left because “nobody should have to live there. It wasn’t conceived for habitation, at least not within the last billion years. It’s so old. You feel it in the stones, the terrible old age”.

Kim Stanley Robinson’s Mars trilogy (published between 1992–1996), Mars is colonized and then terraformed over the course of many centuries. Ben Bova’s Grand Tour series – which deals with the colonization of the Solar System – also includes a novel titled Mars (1992). In this novel, explorers travel to Mars – locations including Mt. Olympus and Valles Marineris – to determine is Mars is worth colonizing.

Alastair Reynolds’ short story “The Great Wall of Mars” (2000) takes place in a future where the most technologically advanced humans are based on Mars and embroiled in an interplanetary war with a faction that takes issue with their experiments in human neurology.

Artist's impression of the terraforming of Mars, from its current state to a livable world. Credit: Daein Ballard
Artist’s impression of the terraforming of Mars, from its current state to a livable world. Credit: Daein Ballard

In Hannu Rajaniemi’s The Quantum Thief (2010), we get a glimpse of Mars in the far future. The story centers on the city of Oubliette, which moves across the face of the planet. Andry Weir’s The Martian (2011) takes place in the near future, where an astronaut is stranded on Mars and forced to survive until a rescue party arrives.

Kim Stanley Robinson’s 2312 (2012) takes place in a future where humanity has colonized much of the Solar System. Mars is mentioned in the course of the story as a world that has been settled and terraformed (which involved lasers cutting canals similar to what Schiaparelli described) and now has oceans covering much of its surface.

Proposed Methods:

NASA’s proposed manned mission to Mars – which is slated to take place during the 2030s using the Orion Multi-Purpose Crew Vehicle (MPCV) and the Space Launch System (SLS) – is not the only proposal to send humans to the Red Planet. In addition to other federal space agencies, there are also plans by private corporations and non-profits, some of which are far more ambitious than mere exploration.

The European Space Agency (ESA) has long-term plans to send humans, though they have yet to build a manned spacecraft. Roscosmos, the Russian Federal Space Agency, is also planning a manned Mars mission, with simulations (called Mars-500) having been completed in Russia back in 2011. The ESA is currently participating in these simulations as well.

In 2012, a group of Dutch entrepreneurs revealed plans for a crowdfunded campaign to establish a human Mars base, beginning in 2023. Known as Mars One, the plan calls for a series of one-way missions to establish a permanent and expanding colony on Mars, which would be financed with the help of media participation.

Mars-manned-mission vehicle (NASA Human Exploration of Mars Design Reference Architecture 5.0) feb 2009. Credit: NASA
Mars-manned-mission vehicle (NASA Human Exploration of Mars Design Reference Architecture 5.0) Feb 2009. Credit: NASA

Other details of the MarsOne plan include sending a telecom orbiter by 2018, a rover in 2020, and the base components and its settlers by 2023. The base would be powered by 3,000 square meters of solar panels, and the SpaceX Falcon 9 Heavy rocket would be used to launch the hardware. The first crew of 4 astronauts would land on Mars in 2025; then, every two years, a new crew of 4 astronauts would arrive.

On December 2nd, 2014, NASA’s Advanced Human Exploration Systems and Operations Mission Director Jason Crusan and Deputy Associate Administrator for Programs James Reuther announced tentative support for the Boeing “Affordable Mars Mission Design.” Currently planned for the 2030s, the mission profile includes plans for radiation shielding, centrifugal artificial gravity, in-transit consumable resupply, and a return-lander.

SpaceX and Tesla CEO Elon Musk also announced plans to establish a colony on Mars with a population of 80,000 people. Intrinsic to this plan is the development of the Mars Colonial Transporter (MCT), a spaceflight system that would rely on reusable rocket engines, launch vehicles, and space capsules to transport humans to Mars and return to Earth.

As of 2014, SpaceX has begun developing the large Raptor rocket engine for the Mars Colonial Transporter, and a successful test was announced in September of 2016. In January 2015, Musk said that he hoped to release details of the “completely new architecture” for the Mars transport system in late 2015.

In June 2016, Musk stated in the first unmanned flight of the Mars transport spacecraft would take place in 2022, followed by the first manned MCT Mars flight departing in 2024. In September 2016, during the 2016 International Astronautical Congress, Musk revealed further details of his plan, which included the design for an Interplanetary Transport System (ITS) and estimated costs.

There may come a day when, after generations of terraforming and numerous waves of colonists, that Mars will begin to have a viable economy as well. This could take the form of mineral deposits being discovered and then sent back to Earth for sale. Launching precious metals, like platinum, off the surface of Mars would be relatively inexpensive thanks to its lower gravity.

But according to Musk, the most likely scenario (at least for the foreseeable future) would involve an economy based on real estate. With human populations exploding all over Earth, a new destination that offers plenty of room to expand is going to look like a good investment.

And once transportation issues are worked out, savvy investors are likely to start buying up land. Plus, there is likely to be a market for scientific research on Mars for centuries to come. Who knows what we might find once planetary surveys really start to open up!

Over time, many or all of the difficulties in living on Mars could be overcome through the application of geoengineering (aka. terraforming). Using organisms like cyanobacteria and phytoplankton, colonists could gradually convert much of the CO² in the atmosphere into breathable oxygen.

In addition, it is estimated that there is a significant amount of carbon dioxide (CO²) in the form of dry ice at the Martian south pole, not to mention absorbed by in the planet’s regolith (soil). If the temperature of the planet were raised, this ice would sublimate into gas and increase atmospheric pressure. Although it would still not be breathable by humans, it would be sufficient enough to eliminate the need for pressure suits.

A possible way of doing this is by deliberately triggering a greenhouse effect on the planet. This could be done by importing ammonia ice from the atmospheres of other planets in our Solar System. Because ammonia (NH³) is mostly nitrogen by weight, it could also supply the buffer gas needed for a breathable atmosphere – much as it does here on Earth.

Similarly, it would be possible to trigger a greenhouse effect by importing hydrocarbons like methane – which is common in Titan’s atmosphere and on its surface. This methane could be vented into the atmosphere where it would act to compound the greenhouse effect.

Zubrin and Chris McKay, an astrobiologist with NASA’s Ames Research center, have also suggested creating facilities on the surface that could pump greenhouse gases into the atmosphere, thus triggering global warming (much as they do here on Earth).

Other possibilities exist as well, ranging from orbital mirrors that would heat the surface to deliberately impacting the surface with comets. But regardless of the method, possibilities exist for transforming Mars’ environment that could make it more suitable for humans in the long run – many of which we are currently doing right here on Earth (with less positive results).

Another proposed solution is building habitats underground. By building a series of tunnels that connect between subterranean habitats, settlers could forgo the need for oxygen tanks and pressure suits when they are away from home.

Additionally, it would provide protection against radiation exposure. Based on data obtained by the Mars Reconnaissance Orbiter, it is also speculated that habitable environments exist underground, making it an even more attractive option.

Potential Benefits:

As already mentioned, there are many interesting similarities between Earth and Mars that make it a viable option for colonization. For starters, Mars and Earth have very similar lengths of days. A Martian day is 24 hours and 39 minutes, which means that plants and animals – not to mention human colonists – would find that familiar.

This diagram shows the distances of the planets in the Solar System (upper row) and in the Gliese 581 system (lower row), from their respective stars (left). The habitable zone is indicated as the blue area, showing that Gliese 581 d is located inside the habitable zone around its low-mass red star. Based on a diagram by Franck Selsis, Univ. of Bordeaux. Credit: ESO
Diagram showing the habitable zones of the Solar System (upper row) and the Gliese 581 system (lower row). Based on a diagram by Franck Selsis, Univ. of Bordeaux. Credit: ESO

Mars also has an axial tilt that is very similar to Earth’s, which means it has the same basic seasonal patterns as our planet (albeit for longer periods of time). Basically, when one hemisphere is pointed towards the Sun, it experiences summer while the other experiences winter – complete with warmer temperatures and longer days.

This too would work well when it comes to growing seasons and would provide colonists with a comforting sense of familiarity and a way of measuring out the year. Much like farmers here on Earth, native Martians would experience a “growing season”, a “harvest”, and would be able to hold annual festivities to mark the changing of the seasons.

Also, much like Earth, Mars exists within our Sun’s habitable zone (aka. “Goldilocks zone“), though it is slightly towards its outer edge. Venus is similarly located within this zone, but its location on the inner edge (combined with its thick atmosphere) has led to it becoming the hottest planet in the Solar System. That, combined with its sulfuric acid rains makes Mars a much more attractive option.

Additionally, Mars is closer to Earth than the other Solar planets – except for Venus, but we already covered why it’s not a very good option! This would make the process of colonizing it easier. In fact, every few years when the Earth and Mars are at opposition – i.e. when they are closest to each other – the distance varies, making certain “launch windows” ideal for sending colonists.

For example, on April 8th, 2014, Earth and Mars were 92.4 million km (57.4 million miles) apart at opposition. On May 22nd, 2016, they will be 75.3 million km (46.8 million miles) apart, and by July 27th of 2018, a meager 57.6 million km (35.8 million miles) will separate our two worlds. During these windows, getting to Mars would be a matter of months rather than years.

Also, Mars has vast reserves of water in the form of ice. Most of this water ice is located in the polar regions, but surveys of Martian meteorites have suggested that much of it may also be locked away beneath the surface. This water could be extracted and purified for human consumption easily enough.

In his book, The Case for Mars, Robert Zubrin also explains how future human colonists might be able to live off the land when traveling to Mars, and eventually colonize it. Instead of bringing all their supplies from Earth – like the inhabitants of the International Space Station – future colonists would be able to make their own air, water, and even fuel by splitting Martian water into oxygen and hydrogen.

Global map of Water ice on Mars
New estimates of water ice on Mars suggest there may be large reservoirs of underground ice at non-polar latitudes. Credit: Feldman et al., 2011

Preliminary experiments have shown that Mars soil could be baked into bricks to create protective structures, which would reduce the amount of material that needs to be shipped to the surface. Earth plants could eventually be grown in Martian soil too, assuming they get enough sunlight and carbon dioxide. Over time, planting on the native soil could also help to create a breathable atmosphere.

Challenges:

Despite the aforementioned benefits, there are also some rather monumental challenges to colonizing the Red Planet. For starters, there is the matter of the average surface temperature, which is anything but hospitable. While temperatures around the equator at midday can reach a balmy 20 °C, at the Curiosity site – the Gale Crater, which is close to the equator – typical nighttime temperatures are as low as -70 °C.

The gravity on Mars is also only about 40% of what we experience on Earth’s, which would make adjusting to it quite difficult. According to a NASA report, the effects of zero-gravity on the human body are quite profound, with a loss of up to 5% muscle mass a week and 1% of bone density a month.

Naturally, these losses would be lower on the surface of Mars, where there is at least some gravity. But permanent settlers would still have to contend with the problems of muscle degeneration and osteoporosis in the long run.

The Biosphere 2 project is an attempt to simulate Mars-like conditions on Earth. Credit: Science Photo Library
The Biosphere 2 project is an attempt to simulate Mars-like conditions on Earth. Credit: Science Photo Library

And then there’s the atmosphere, which is unbreathable. About 95% of the planet’s atmosphere is carbon dioxide, which means that in addition to producing breathable air for their habitats, settlers would also not be able to go outside without a pressure suit and bottled oxygen.

Mars also has no global magnetic field comparable to Earth’s geomagnetic field. Combined with a thin atmosphere, this means that a significant amount of ionizing radiation is able to reach the Martian surface.

Thanks to measurements taken by the Mars Odyssey spacecraft’s Mars Radiation Environment Experiment (MARIE), scientists learned that radiation levels in orbit above Mars are 2.5 times higher than at the International Space Station. Levels on the surface would be lower, but would still be higher than human beings are accustomed to.

In fact, a recent paper submitted by a group of MIT researchers – which analyzed the Mars One plan to colonize the planet beginning in 2020 – concluded that the first astronaut would suffocate after 68 days, while the others would die from a combination of starvation, dehydration, or incineration in an oxygen-rich atmosphere.

Artist's concept of a Martian astronaut standing outside the Mars One habitat. Credit: Bryan Versteeg/Mars One
Artist’s concept of a Martian astronaut standing outside the Mars One habitat. Credit: Bryan Versteeg/Mars One

In short, the challenges to creating a permanent settlement on Mars are numerous, but not necessarily insurmountable. And if we do decide, as individuals and as a species, that Mars is to become a second home for humanity, we will no doubt find creative ways to address them all.

Who knows? Someday, perhaps even within our own lifetimes, there could be real Martians. And they would be us!

Universe Today has many interesting articles about the possibility of humans living on Mars. Here’s a great article by Nancy Atkinson about the possibility of a one-way, one-person trip to Mars

What about using microbes to help colonize mars? And if you want to know the distances between Earth and Mars, check it out here.

For more information, check out Mars colonies coming soon, Hubblesite’s News Releases about Mars, and NASA’s Quick Facts

The Mars Society is working to try and colonize Mars. And Red Colony is a great resource of articles about colonizing Mars.

Finally, if you’d like to learn more about Mars in general, we have done several podcast episodes about the Red Planet at Astronomy Cast. Episode 52: Mars, Episode 91: The Search for Water on Mars, and Episode 94: Humans to Mars – Part 1, Scientists.

Reference:
NASA Quest: Possibility of colonizing Mars

Posted on by Matt Williams

The Dwarf Planet Eris

Artist illustration of Eris. Image credit: NASA

Eris is the largest dwarf planet in the Solar System, and the ninth largest body orbiting our Sun. Sometimes referred to as the “tenth planet”, it’s discovery is responsible for upsetting the traditional count of nine planets in our Solar System, as well as leading the way to the creation of a whole new astronomical category.

Located beyond the orbit of Pluto, this “dwarf planet” is both a trans-Neptunian object (TNO), which refers to any planetary object that orbits the Sun at a greater distance than Neptune – or 30 astronomical units (AU). Because of this distance, and the eccentricity of its orbit, it is also a member of a the population of objects (mostly comets) known as the “scattered disk”.

The discovery of Eris was so important because it was a celestial body larger than Pluto, which forced astronomers to consider, for the first time in history, what the definition of a planet truly is.

Discovery:

Eris, which has the full title of 136199 Eris, was first observed in 2003 during a Palomar Observatory survey of the outer solar system by a team led by Mike Brown, a professor of planetary astronomy at the California Institute of Technology. The discovery was confirmed in January 2005 after the team examined the pictures obtained from the survey in detail.

Classification:

At the time of it’s discovery, Brown and his colleagues believed that they had located the 10th planet of our solar system, since it was the first object in the Kuiper Belt found to be bigger than Pluto. Some astronomers agreed and liked the designation, but others objected since they claimed that Eris was not a true planet. At the time, the definition of “planet” was not a clear-cut since there had never been an official definition issued by the International Astronomical Union (IAU).

The matter was settled by the IAU in the summer of 2006. They defined a planet as an object that orbits the Sun, which is large enough to make itself roughly spherical. Additionally, it would have to be able to clear its neighborhood – meaning it has enough gravity to force any objects of similar size or that are not under its gravitational control out of its orbit.

In addition to finally defining what a planet is, the IAU also created a new category of “dwarf planets“. The only difference between a planet and a dwarf planet is that a dwarf planet has not cleared its neighborhood. Eris was assigned to this new category, and Pluto lost its status as a planet. Other celestial bodies, including Haumea, Ceres, and Makemake, have been classified as dwarf planets.

artist's impression shows the distant dwarf planet Eris. New observations have shown that Eris is smaller than previously thought and almost exactly the same size as Pluto. Eris is extremely reflective and its surface is probably covered in frost formed from the frozen remains of its atmosphere. Credit: ESO
Artist’s impression shows the distant dwarf planet Eris, highlighting its bright surface. Credit: ESO

Naming:

Eris is named after the Greek goddess of strife and discord. The name was assigned on September 13th, 2006, following an unusually long consideration period that arose over the issue of classification. During this time, the object became known to the wider public as Xena, which was the name given to it by the discovery team.

The team had been saving this name, which was inspired by the title character of the television series Xena: Warrior Princess, for the first body they discovered that was larger than Pluto. They also chose it because it started with the letter X, a reference to Percival Lowell’s hunt for a planet he believed to exist the edge of the Solar System (which he referred to as “Planet X“).

According to fellow astronomer and science writer Govert Schilling, Brown initially wanted to call the object “Lila”. This name was inspired by a concept in Hindu mythology that described the cosmos as the outcome of a game played by Brahma, and also because it was similar to “Lilah” – the name of Brown’s newborn daughter.

Size and Orbit:

The actual size and mass of Eris has been the subject of debate, as official estimates have changed with time and subsequent viewing. In 2005, using images from the Hubble Space Telescope. the diameter of Eris was measured to be 2397 ± 100 km (1,489 miles). In 2007, a series of observations of the largest trans-Neptunian objects with the Spitzer Space Telescope estimated Eris’s diameter at 2600 (+400/-200) km (1616 miles).

A diagram showing solar system orbits. The highly tilted orbit of Eris is in red. Credit: NASA
A diagram showing solar system orbits. The highly tilted orbit of Eris is in red. Credit: NASA

The most recent observation took place in November of 2010, when Eris was the subject of one of the most distant stellar occultations yet achieved from Earth. The teams findings were announced on October 2011, and contradicted previous findings with an estimated diameter of 2326 ± 12 km (1445 miles).

Because of these differences, astronomers have been hard-pressed to maintain that Eris is more massive than Pluto. According to the latest estimates, the Solar System’s “ninth planet” has a diameter of 2368 km (1471 miles), placing it on par with Eris. Part of the difficulty in accurately assessing the planet’s size comes from interference from Pluto’s atmosphere. Astronomers expect a more accurate appraisal when the New Horizons space probe arrives at Pluto in July 2015.

Eris has an orbital period of 558 years. Its maximum possible distance from the Sun (aphelion) is 97.65 AU, and its closest (perihelion) is 37.91 AU. This means that Eris and its moon are currently the most distant known objects in the Solar System, apart from long-period comets and space probes.

Eris’s orbit is highly eccentric, and brings Eris to within 37.9 AU of the Sun, a typical perihelion for scattered objects. This is within the orbit of Pluto, but still safe from direct interaction with Neptune (29.8-30.4 AU). Unlike the eight planets, whose orbits all lie roughly in the same plane as the Earth’s, Eris’s orbit is highly inclined – the planet is tilted at an angle of about 44° to the ecliptic.

Moons:

Eris has one moon called Dysnomia, which is named after the daughter of Eris in Greek mythology, which was first observed on September 10th, 2005 – a few months after the discovery of Eris. The moon was spotted by a team using the Keck telescopes in Hawaii, who were busy carrying out observations of the four brightest TNOs (Pluto, Makemake, Haumea, and Eris) at the time.

Eris (center) and its moon of Dysnomia (left of center), taken by the Hubble Space Telescope. Credit: NASA/ESA/Mike Brown
Eris (center) and its moon of Dysnomia (left of center), taken by the Hubble Space Telescope. Credit: NASA/ESA/Mike Brown

Interesting Facts:

The dwarf planet is rather bright and can be detected using something as simple as a small telescope. Models of internal heating via radioactive decay suggest that Eris may be capable of sustaining an internal ocean of liquid water at the mantle-core boundary. These studies were conducted by Hauke Hussmann and colleagues from the Institute of Astronomy, Geophysics and Atmospheric Sciences (IAG) at the University of São Paulo.

Brown and the discovery team followed up their initial identification of Eris with spectroscopic observations of the planet, which were made on January 25th, 2005. Infrared light from the object revealed the presence of methane ice, indicating that the surface may be similar to that of Pluto and of Neptune’s moon Triton.

Due to Eris’s distant eccentric orbit, its surface temperature is estimated to vary between about 30 and 56 K (?243.2 and ?217.2 °C). This places it on par with Pluto’s surface temperature, which ranges from 33 to 55 K (-240.15 and -218.15 °C).

We have many interesting articles on planets here at Universe Today, including this article on What is the newest planet and the 10th planet.

If you are looking for more information, try Eris and NASA’s Solar System Exploration entry.

Astronomy Cast has an episode on Pluto’s planetary identity crisis.

Source:

Posted on by Matt Williams

America’s First Space Station: The NASA Skylab

Skylab, America’s First manned Space Station. Photo taken by departing Skylab 4 crew in Feb. 1974. Credit: NASA

Before there was the International Space Station, before there was Mir, there was Skylab. Established in 1973, and remaining in orbit until 1979, this orbital space station was American’s first long-duration orbital workshop, and the ancestor of all those that have followed.

Originally conceived of in 1969, the plans for the station were part of a general winding down that took place during the last years of the Space Race – which officially ran from 1955 to 1972. Having sent astronauts into orbit and achieved the dream of manned missions to the Moon, the purpose of Skylab was to achieve a lasting presence in space. Rather than simply “getting there first”, NASA was now concerned with staying there.

Planning:

The seeds of Skylab were planted as early as 1959, when Wernher von Braun – the head of the Development Operations Division at the Army Ballistic Missile Agency – proposed a mission that would use a multistage rocket to place men on the Moon. As part of this mission, the upper stage of the rocket would be deposited around the Earth to function as an orbital laboratory. Known as Horizon, these plans were eventually be seized upon by NASA, which was rapidly forming at the time.

A 1967 conceptual drawing of the Gemini B reentry capsule separating from the MOL at the end of a mission. Credit: NASA
A 1967 conceptual drawing of the Gemini B reentry capsule separating from the MOL at the end of a mission. Credit: NASA

Similarly, as of September 1963, the US Department of Defense (DoD) and NASA began collaborating on a manned facility known as the “Manned Orbital Laboratory” (MOL). The initial DoD plan called for a station that would be the same diameter as a Titan II upper stage, and which would primarily be intended for photo reconnaissance using large telescopes directed by a two-man crew.

As the head of the Marshall Space Flight Center during the 1960s, Von Braun became concerned that his employees would not have work beyond developing the Saturn rockets intended for the Apollo program. As a result, he began advocating for the creation of a space station using modified Apollo hardware – which included the S-II second stage of a Saturn V rocket.

Throughout 1965, several more proposals were considered that relied on the Saturn S-IVB stage to create a space station. As part of NASA’s The Orbital Workshop program, this proposal also called for sending a crew to man the station using a Apollo Command-Service Module (CSM) aboard a Saturn IB rocket.

This artist's concept is a cutaway illustration of the Skylab with the Command/Service Module being docked to the Multiple Docking Adapter. Credit: NASA
This artist’s concept is a cutaway illustration of the Skylab with the Command/Service Module being docked to the Multiple Docking Adapter. Credit: NASA

The crew would dock with the station, vent the residual propellants from the S-IVB stage, fill the hydrogen tank with a breathable oxygen atmosphere, and then enter the tank and outfit it as a station. On August 8th, 1969, after years of development and workshops, the McDonnel Douglas Corporation received a contract to create an Orbital Workshop out of two existing S-IVB stages.

In February of 1970, the program was renamed “Skylab” as a result of a NASA contest. A Saturn V rocket that was originally produced for the Apollo program – before the cancellation of Apollo 18, 19, and 20 – was re-purposed and redesigned to carry the station into orbit.

Launch:

Skylab was launched on May 14th, 1973 on a mission that is sometimes referred to as Skylab 1 (or SL-1). Severe damage was sustained during the launch when the station’s meteoroid shield and one of the two solar panels tore off due to vibrations.

Since the station was designed to face the Sun in order to get as much power as possible, and the shield was ripped off, the station rose to a temperature of 52°C. As a result, scientists had to move the space station and effect repairs before astronauts could be dispatched to it.

Launch of the modified Saturn V rocket carrying the Skylab space station. Credit: NASA
Launch of the modified Saturn V rocket carrying the Skylab space station. Credit: NASA

Missions:

The first manned mission (designated Skylab 2, or SL-2) took place on May 25th, 1973, atop a Saturn IB and involved extensive repairs to the station. This mission last four weeks, and astronauts Charles Conrad, Jr., Paul J. Weitz, Joseph P. Kerwin were the crew members. During the mission, the crew conducted a number of experiments, including solar astronomy and medical studies, and three EVAs (extra-vehicular activities) were completed as well.

The second manned mission, also known as Skylab 3 (SL-3), was launched on July 28th, 1973. The crew consisted of Alan L. Bean, Jack R. Lousma, and Owen K. Garriott. The mission lasted 59 days and 11 hours, during which time the crew carried out additional repairs as well as performing scientific and medical experiments.

The third and final mission to the Skylab (Skylab 4, SL-4) was the longest, lasting 84 days and one hour. Gerald P. Carr, William R. Pogue, Edward G. Gibson were the crew, and in addition to performing various experiments, they also observed the Comet Kohoutek. The crew conducted three EVAs which lasted a total of 22 hours and 13 minutes.

Skylab in February 1974, pictured by the SL-4 crew as they departed the station to return to Earth. Credit: NASA
Skylab in February 1974, pictured by the SL-4 crew as they depart the station to return to Earth. Credit: NASA

Skylab was occupied a total of 171 days and orbited the Earth more than 2,476 times during the course of its service. Each Skylab mission set a record for the amount of time astronauts spent in space.

Decommissioning:

Though NASA hoped that the station would remain in orbit for ten years, by 1977, it became clear that it would not be able to maintain a stable orbit for that long. As a result, after SL-4, preparations were made to shut down all operations and de-orbit the station.

Skylab’s demise was an international media event, with merchandising of T-shirts and hats with bullseyes, wagering on the time and place of re-entry, and nightly news reports. In the hours before re-entry, ground controllers adjusted Skylab’s orientation to try to minimize the risk of re-entry on a populated area.

They aimed the station at a spot 1,300 km (810 miles) south southeast of Cape Town, South Africa, and re-entry began at approximately 16:37 UTC, July 11, 1979. The debris reached Earth on July 11th, 1979, raining down over the Indian Ocean and parts of Australia.

On May 13, NASA commemorated the 40th anniversary of Skylab’s liftoff with a special roundtable discussion broadcast live on NASA TV. The event took place at NASA’s Headquarters in Washington, DC, and participants included Skylab and current ISS astronauts and NASA human spaceflight managers.

While the station did not have the history of service that NASA initially hoped for, the development, deployment and crewed missions to Skylab were essential to the creation of the International Space Station, which began almost 20 years after Skylab came home.

We have many interesting articles on the Apollo program and space stations here at Universe Today. For example, here are some articles on Apollo 20 and the International Space Station.

You should also check out Skylab and NASA Skylab. Astronomy Cast has an episode on space elevators.

Source: NASA

Posted on by Matt Williams

What is Lunar Regolith?

A boot print on the lunar regolith. Credit: NASA.

When you’re walking around on soft ground, do you notice how your feet leave impressions? Perhaps you’ve tracked some of the looser earth in your yard into the house on occasion? If you were to pick up some of these traces – what we refer to as dirt or soil – and examine them beneath a microscope, what would you see?

Essentially, you would be seeing the components of what is known as regolith, which is a collection of particles of dust, soil, broken rock, and other materials found here on Earth. But interestingly enough, this same basic material can be found in other terrestrial environments as well – including the Moon, Mars, other planets, and even asteroids.

Definition:

The term regolith refers to any layer of material covering solid rock, which can come in the form of dust, soil or broken rock. The word is derived from the combination of two Greek words – rhegos (which means “blanket”) and lithos (which means “rock).

Earth:

On Earth, regolith takes the form of dirt, soil, sand, and other components that are formed as a result of natural weathering and biological processes. Due to a combination of erosion, alluvial deposits (i.e. moving water deposing sand), volcanic eruptions, or tectonic activity, the material is slowly ground down and laid out over solid bedrock.

central Yilgarn Craton, Western Australia.
Picture of Mt Magnet in the Central Yilgarn Craton in Western Australia, which dates to the Precambrian Era. Credit: geomorphologie.revues.org

It can be made up of clays, silicates, various minerals, groundwater, and organic molecules. Regolith on Earth can vary from being essentially absent to being hundreds of meters thick. Its can also be very young (in the form of ash, alluvium, or lava rock that was just deposited) to hundreds of millions of years old (regolith dating to the Precambrian age occurs in parts of Australia).

On Earth, the presence of regolith is one of the important factors for most life, since few plants can grow on or within solid rock and animals would be unable to burrow or build shelter without loose material. Regolith is also important for human beings since it has been used since the dawn of civilization (in the form of mud bricks, concrete and ceramics) to build houses, roads, and other civil works.

The difference in terminology between “soil” (aka. dirt, mud, etc.) and “sand” is the presence of organic materials. In the former, it exists in abundance, and is what separates regolith on Earth from most other terrestrial environments in our Solar System.

The Moon:

The surface of the Moon is covered with a fine powdery material that scientists refer to it as “lunar regolith”. Nearly the entire lunar surface is covered with regolith, and bedrock is only visible on the walls of very steep craters.

Earth viewed from the Moon by the Apollo 11 spacecraft. Credit: NASA
Earth viewed from the Moon by the Apollo 11 spacecraft, across a sea of lunar soil. Credit: NASA

The Moon regolith was formed over billions of years by constant meteorite impacts on the surface of the Moon. Scientists estimate that the lunar regolith extends down 4-5 meters in some places, and even as deep as 15 meters in the older highland areas.

When the plans were put together for the Apollo missions, some scientists were concerned that the lunar regolith would be too light and powdery to support the weight of the lunar lander. Instead of landing on the surface, they were worried that the lander would just sink down into it like a snowbank.

However, landings performed by robotic Surveyor spacecraft showed that the lunar soil was firm enough to support a spacecraft, and astronauts later explained that the surface of the Moon felt very firm beneath their feet. During the Apollo landings, the astronauts often found it necessary to use a hammer to drive a core sampling tool into it.

Once astronauts reached the surface, they reported that the fine moon dust stuck to their spacesuits and then dusted the inside of the lunar lander. The astronauts also claimed that it got into their eyes, making them red; and worse, even got into their lungs, giving them coughs. Lunar dust is very abrasive, and has been noted for its ability to wear down spacesuits and electronics.

Alan Bean Takes Lunar Soil Sample
Alan Bean takes a sample of lunar regolith during the Apollo 12 mission. Credit: NASA

The reason for this is because lunar regolith is sharp and jagged. This is due to the fact that the Moon has no atmosphere or flowing water on it, and hence no natural weathering process. When the micro-meteoroids slammed into the surface and created all the particles, there was no process for wearing down its sharp edges.

The term lunar soil is often used interchangeably with “lunar regolith”, but some have argued that the term “soil” is not correct because it is defined as having organic content. However, standard usage among lunar scientists tends to ignore that distinction. “Lunar dust” is also used, but mainly to refer to even finer materials than lunar soil.

As NASA is working on plans to send humans back to the Moon in the coming years, researchers are working to learn the best ways to work with the lunar regolith. Future colonists could mine minerals, water, and even oxygen out of the lunar soil, and use it to manufacture bases with as well.

Mars:

Landers and rovers that have been sent to Mars by NASA, the Russians and the ESA have returned many interesting photographs, showing a landscape that is covered with vast expanses of sand and dust, as well as rocks and boulders.

A successful scoop of Martian regolith (NASA/JPL-Caltech/University of Arizona/Max Planck Institute)
A successful scoop of Martian regolith performed by NASA’s Phoenix lander. Credit: NASA/JPL-Caltech/University of Arizona/Max Planck Institute

Compared to lunar regolith, Mars dust is very fine and enough remains suspended in the atmosphere to give the sky a reddish hue. The dust is occasionally picked up in vast planet-wide dust storms, which are quite slow due to the very low density of the atmosphere.

The reason why Martian regolith is so much finer than that found on the Moon is attributed to the flowing water and river valleys that once covered its surface. Mars researchers are currently studying whether or not martian regolith is still being shaped in the present epoch as well.

It is believed that large quantities of water and carbon dioxide ices remain frozen within the regolith, which would be of use if and when manned missions (and even colonization efforts) take place in the coming decades.

Mars moon of Deimos is also covered by a layer of regolith that is estimated to be 50 meters (160 feet) thick. Images provided by the Viking 2 orbiter confirmed its presence from a height of 30 km (19 miles) above the moon’s surface.

Asteroids and Outer Solar System:

The only other planet in our Solar System that is known to have regolith is Titan, Saturn’s largest moon. The surface is known for its extensive fields of dunes, though the precise origin of them are not known. Some scientists have suggested that they may be small fragments of water ice eroded by Titan’s liquid methane, or possibly particulate organic matter that formed in Titan’s atmosphere and rained down on the surface.

Another possibility is that a series of powerful wind reversals, which occur twice during a single Saturn year (30 Earth years), are responsible for forming these dunes, which measure several hundred meters high and stretch across hundreds of kilometers.  Currently, Earth scientists are still not certain what Titan’s regolith is composed of.

Data returned by the Huygens Probe’s penetrometer indicated that the surface may be clay-like, but long-term analysis of the data has suggested that it may be composed of sand-like ice grains.  The images taken by the probe upon landing on the moon’s surface show a flat plain covered in rounded pebbles, which may be made of water ice, and suggest the action of moving fluids on them.

Asteroids have been observed to have regolith on their surfaces as well. These are the result of meteoriod impacts that have taken place over the course of millions of years, pulverizing their surfaces and creating dust and tiny particles that are carried within the craters.

False color picture of Eros' 5.3-kilometer (3.3-mile) surface crater, showing regolith inside. Credit: NASA/JPL/JHUAPL
False color picture taken by NASA’s NEAR Shoemaker camera of Eros’ 5.3-kilometer (3.3-mile) surface crater, showing the presence of regolith inside. Credit: NASA/JPL/JHUAPL

NASA’s NEAR Shoemaker spacecraft produced evidence of regolith on the surface of the asteroid 433 Eros, which remains the best images of asteroid regolith to date. Additional evidence has been provided by JAXA’s Hayabusa mission, which returned clear images of regolith on an asteroid that was thought to be too small to hold onto it.

Images provided by the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) cameras on board the Rosetta Spacecraft confirmed that the asteroid 21 Lutetia has a layer of regolith near its north pole, which was seen to flow in major landslides associated with variations in the asteriod’s albedo.

To break it down succinctly, wherever there is rock, there is likely to be regolith. Whether it is the product of wind or flowing water, or the presence of meteors impacting the surface, good old fashioned “dirt” can be found just about anywhere in our Solar System; and most likely, in the universe beyond…

We’ve done several articles about the Moon’s regolith here on Universe Today. Here’s a way astronauts might be able to extract water from lunar regolith with simple kitchen appliances, and an article about NASA’s search for a lunar digger.

Want to buy some lunar regolith simulant? Here’s a site that lets you buy it. Do you want to be a Moon miner? There’s lots of good metal in that lunar regolith.

You can listen to a very interesting podcast about the formation of the Moon from Astronomy Cast, Episode 17: Where Did the Moon Come From?

Reference:
NASA